MCP1632-BAESLASHMS datasheet(17/34 Pages) MICROCHIP

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DS20005254A-page 17

MCP1632

5.0

APPLICATION CIRCUITS

5.1

Typical Applications

The MCP1632 PWM controller can be used for

applications that require low-side MOSFET control,

such as Boost, Buck-Boost, Flyback, SEPIC or Ćuk

converters. By using an external high-side MOSFET

driver (e.g. MCP14628), the MCP1632 device is able to

control the buck converter. The MCP1632 PWM

controller

can

easily

interfaced

with

microcontroller in order to develop intelligent solutions,

such as battery chargers or LED drivers.

Figure 5-1 depicts the typical boost converter

controlled by MCP1632. The input voltage applied on

the VIN pin of the MCP1632 device should be kept

below 5.5V. If the converter must operate with input

voltages higher than 5.5V, a linear voltage regulator

can be used to bias the MCP1632 controller. The Peak

Current Mode control used in this case will ensure

consistent performance over a wide range of operating

conditions.

The Q1 MOSFET is protected against overcurrent by

internally limiting the maximum voltage at the output of

the error amplifier of the controller. If the voltage

applied on the CS pin exceeds 0.9V, the MCP1632

device will reduce the duty cycle in order to prevent

overcurrent in Q1 MOSFET. The maximum drain peak

current in Q1 can be calculated using Equation 5-1.

The slope compensation ramp amplitude may limit the

maximum peak current and must be considered when

calculating this parameter. The DC offset of the slope

compensation ramp (DCHIGH) is calculated using the

equations provided in Figure 4-3.

Note that the boost converter is not protected against

the output short circuit.

EQUATION 5-1:

FIGURE 5-1:

MCP1632 Boost Converter.

Peak

Max A



0.9V

HIGH





–

SENSE





--------------------------------------------------------------

MCP1632

RVREF

CSS

VIN

VOUT

VREF

COMP

VEXT

GND

VIN

LDO

RSENSE

RSLOPE

CIN

COUT

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